There are many different vascular abnormalities that require medical treatment. One of the more commonly treated abnormalities is a vascular aneurysm. Vascular aneurysms are abnormal enlargements of a blood vessel that may result from disease or genetic predisposition. Aneurysms may occur in any blood vessel, but many of them occur in the abdominal aorta. If left untreated, aneurysms may rupture leading to almost certain fatality.
Aneurysms are commonly treated by either bypassing the affected portion or filling the aneurysm. A bypass procedure involves the implantation of an artificial vascular graft with one end upstream of the aneurysm and a second end downstream of the aneurysm. After the graft is implanted, the blood flow bypasses the aneurysm by flowing through the graft. Alternatively, a device or substance may be injected into the aneurysm to permanently fill it.
A major disadvantage of conventional treatments for aneurysms has been that the blood flow through the affected vessel had to be blocked in order to perform the treatments efficiently. In the case of bypass surgery, the blood flow must be blocked upstream of the location where the upstream end of the graft will be implanted to avoid excessive blood loss. Where the treatment involves the implantation of a device within the aneurysm, the blood flow must be blocked upstream of the aneurysm so that the device may be placed properly. Similarly, where a substance is injected into certain forms of aneurysms (e.g., fusiform aneurysms) it may be necessary to block the blood flow upstream of the aneurysm so that the substance is not swept away during injection.
An arterial stenosis is another vascular abnormality that is commonly treated. A stenosis is a constriction of a vessel that may be created by formations of material deposits on the wall of a vessel or by thickening of the vessel wall itself. Such a narrowing of a vessel limits the amount of oxygenated blood reaching downstream organs and may trigger other medical conditions such as heart attacks.
Various treatments have also been developed to treat stenoses. The treatments typically rely on either surgical intervention or catheter-based therapies. One such surgical procedure for treating material formations is percutaneous transluminal coronary angioplasty, commonly referred to as “angioplasty” or “PTCA”. The objective in angioplasty is to enlarge the lumen of the affected coronary artery by radial hydraulic expansion. PTCA is performed by inflating a balloon on a balloon catheter within the narrowed region of the vessel. Depending on the characteristics of the particular formation, it may be compressed or cracked and split by the inflated balloon. Alternatively, a dissolution agent may be applied to a material formation to cause the formation to dissolve and disengage the vessel wall. Unfortunately, the treatments for stenoses often suffer from problems similar to those associated with the treatment of aneurysms.
Isolation devices have been created to remedy some of the problems associated with the treatment of vascular abnormalities. Those devices have typically utilized a central body with a series of balloons disposed about the body. In order to inflate the balloons, at least one lumen was extended from a fluid source and through the central body to the balloons. The inflated balloons were used to completely isolate an annular volume between the balloons, the exterior surface of the central body and the vessel wall from the flow of blood. Oftentimes, small openings through the wall of the central body, located upstream of the balloons, allowed a limited amount of blood to enter and flow through a small central lumen in the body past the balloons and isolated volume.
Those isolation devices presented many disadvantages. First, the reliance on balloons as the sealing mechanism required that additional hardware be connected to the catheter outside of the patient's body, which makes it more cumbersome to make and use a small catheter. Second, catheters relying on balloons requires additional care to assure fluid tight seals are created during manufacture. In addition, balloon catheters pose a risk of fluid leakage from the balloon during use resulting in the loss of the seal between the balloon and the vessel wall. Finally, balloon devices are typically not self-expanding.
A need exists for a device that efficiently isolates a space within a vessel from the flow of blood, while allowing blood to flow past the isolated space, that is more reliable, more convenient to use, and easier to manufacture.